The invention relates to a method and devices for the transfer of information from a photographic field lens to a corresponding photographic camera, wherein the information is converted into electrical signals.
A device is known in which an electrical resistance value from a mechanical-electrical converter disposed in the photographic field lens is represented corresponding to the respective diaphragm setting and is transmitted by way of several contacts corresponding to each other on the objective and on the camera into a bridge circuit provided in the camera.
According to German Offenlegungsschrift No. 2,849,932, the contacts for information input of adjustable f-numbers in this device are disposed such that a piece of information can be formed by way of a coding arrangement independent from the diaphragm setting mechanism, which information corresponds to the region of adjustable diaphragm values defined by the limiting values "largest opening" and "smallest opening".
In addition, a camera with automatic focussing is described in German Offenlegungsschrift No. 3,006,068, in which the electrical signals controlling the focussing of the interchangeable field lenses are led via corresponding signal contacts on the camera and lenses.
It is a disadvantage of the two devices that in each case only one piece of information, e.g., the opening of the aperture or the distance of the object, can be transmitted. In addition, a plurality of contacts or contact surfaces are required for the transmission of the information as well as for the power supply.